Many liquid compositions, plastic material, and the like, are prepared in large batches and typically require controlled addition of ingredients, a number of hours of agitation, heating, pressurization, and the like. Since it is most economical to prepare such compositions in relatively large quantities, it is also important to be assured that the batch being prepared meets all of the desired criteria, such as purity, density, viscosity, consistency, pH, color, etc., and that the batch contains all of the correct individual ingredients in their proper proportions.
It is thus quite important to constantly monitor the batch as it undergoes preparation to be assured that the batch meets all of the desired criteria during each phase of preparation, and further to enable appropriate corrective measures to be undertaken promptly to prevent the rather expensive loss of a batch as a result of failure to undertake proper monitoring and corrective measures, when necessary. Many batches under preparation require that certain elevated temperature levels and/or pressure levels be maintained throughout the mixing and preparing phases, placing severe restraints on the type of apparatus which may be utilized to extract a sample.
The tank containing the batch being monitored is typically rather tall, i.e., taller than the average person. The ingredients are generally added at the top of the tank. The exhaust ducting (if any) and often the heating fluids and/or coolants are normally inserted and/or removed from the top of the tank. As a result it is most advantageous to locate all instrumentation and analytical instrumentation in the same area, at the top of the tank, and to deliver the sample(s) at this area or level.
Such laboratory facilities are frequently located at the level of the top of the tank and extracting samples from the bottom is time consuming. The laboratory is frequently combined with a control panel. In order to extract a sample from the bottom of the tank the operator must absent himself from observation of the control panel for a considerable time if he goes downstairs to extract a sample from the lower portion of the tank.
Also samples drawn from a stagnant section, such as tank protuberance, nozzle or pipe extending from the vessel or other such arrangement requires withdrawal of sufficient liquid to clear the space of stagnant liquid. Then a separate more representative sample of the batch may be obtained. The sampling system to be described herein-below provides for a continuous rapid flow and thus a continuously representative sample without the necessity of withdrawing (and generally discarding) unrepresentative material.